The present invention relates generally to scanning methods and scanning beam devices. More particularly, the present invention provides improved optical assemblies and improved optical fibers that allow for placement of one or more light detectors within a housing of the scanning beam device.
Conventional endoscopes generally have a separate detector element in its distal tip for every pixel of resolution for the image of the target area. The detector element may be one optical fiber in a fiber bundle or one pixel in a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) image detector chip. As the resolution is increased, the number of detector elements must be increased, thus increasing the diameter of the endoscope. Thus, in order to reduce a size of the endoscope, conventional endoscopes must sacrifice image quality, the quality of the optical assembly, and/or durability.
One proposed endoscope that overcomes some of the drawbacks of the conventional endoscope has been developed by the University of Washington. The endoscope developed by the University of Washington is a scanning beam device that uses a single, cantilevered optical fiber to scan an illumination spot over the target area in a one or two dimensional scan pattern. Light reflected from the target area is sequentially captured by one or more light detectors that are coupled to a distal end of the scanning beam device. Typical detectors include a photo detector, or an optical fiber that relays light to a photo detector that is remote from the distal end of the scanning beam device. The detector response is then used to determine the brightness of the small portion of the image that corresponds to the small area illuminated by the illumination spot at that given point in time during the scanning pattern.
If a monochromatic image of the target area is desired, only a single light detector is needed. However, if it is desired to capture a color image or to perform advance features such as specular reflection reduction, multiple light detectors may be coupled to the distal end of the scanning beam device to collect the back reflected light from the target area.
Advantageously, in contrast to conventional endoscopes, the scanning beam device of the present invention needs only a single detector to function properly, and the scanning beam devices of the present invention do not require additional detector elements to increase the resolution of the resultant image. Consequently, the scanning beam devices of the present invention are able to provide a high resolution image while maintaining a small diameter housing. Because the diameter of the distal portion of the housing is smaller than conventional imaging devices, the scanning beam devices of the present invention are able to provide high resolution images of body lumens that may not be accessible by conventional endoscopes.
To achieve a good signal to noise ratio (SNR)—and thus the clearest images of the target area—Applicants have found that it is desirable to have the detector(s) receive as much reflected light from the target area as possible. Simulations have shown that the reflected light tends to be highest closest to the center of the scanning beam device, and that there is less reflected light at distances farther from the center of the scanning beam device. To maximize the reflected light from the target area, it was thought that it would be best to maximize the surface area of the detector(s) and position the sensor(s) as near to the center of the scanning beam device as possible.
Therefore, what is needed are scanning beam devices that are able to position the detector assembly within the housing so as to receive diffused reflected light.